fix group stop with exit race

[linux-2.6-block.git] / kernel / signal.c

diff --git a/kernel/signal.c b/kernel/signal.c
index 3fca710a5cd7c0a7371c1c9e8519a63468732e76..209eec11eef5dd0ca7662559e9988d7bcbe07056 100644 (file)
--- a/kernel/signal.c
+++ b/kernel/signal.c
@@ -1739,7 +1739,7 @@ static int do_signal_stop(int signr)
                         * stop is always done with the siglock held,
                         * so this check has no races.
                         */
-                       if (!t->exit_state &&
+                       if (!(t->flags & PF_EXITING) &&
                            !task_is_stopped_or_traced(t)) {
                                stop_count++;
                                signal_wake_up(t, 0);
@@ -1900,6 +1900,31 @@ relock:
        return signr;
 }
 
+void exit_signals(struct task_struct *tsk)
+{
+       int group_stop = 0;
+
+       spin_lock_irq(&tsk->sighand->siglock);
+       if (unlikely(tsk->signal->group_stop_count) &&
+                       !--tsk->signal->group_stop_count) {
+               tsk->signal->flags = SIGNAL_STOP_STOPPED;
+               group_stop = 1;
+       }
+
+       /*
+        * From now this task is not visible for group-wide signals,
+        * see wants_signal(), do_signal_stop().
+        */
+       tsk->flags |= PF_EXITING;
+       spin_unlock_irq(&tsk->sighand->siglock);
+
+       if (unlikely(group_stop)) {
+               read_lock(&tasklist_lock);
+               do_notify_parent_cldstop(tsk, CLD_STOPPED);
+               read_unlock(&tasklist_lock);
+       }
+}
+
 EXPORT_SYMBOL(recalc_sigpending);
 EXPORT_SYMBOL_GPL(dequeue_signal);
 EXPORT_SYMBOL(flush_signals);